Logic analyzers have been developed to provide real-time analysis of digital electronic systems. Logic analyzers appear similar to oscilloscopes in that they display a plurality of digital signals on a cathode-ray tube screen; however, it is the combination of such signals at any given point in time that conveys digital information, or data words. The logic analyzer has a separate input and memory channel for each signal, and typically a plurality of channels are provided, depending upon the length of the data word, to simultaneously process and display parallel data bits. Each data channel samples the incoming digital signal at a rate determined by an internal reference clock, and since the digital signal is essentially a stream of pulses, the sampled signal will be either a high or a low value.
Occasionally, spurious or random narrow pulses or noise spikes may appear in a stream of data. These are called glitches, and may result in erroneous data acquisition, or undesired triggering, or false signals to be generated. Thus it is desirable to detect glitches which occur within a sample clock period so as to negate or correct errors which the glitch may have caused. Prior art glitch detector circuits are complex and have limitations, such as inability to detect glitches on every clock cycle and inability to detect second-order glitches (those with three transitions rather than two).